1. Field of the Invention
The invention relates to the field of vehicle tire assemblies and, in particular, to a tire assembly that can be stored on the rim in a collapsed condition and inflated when use is required.
2. Description of Related Art
Vehicle tires designed for the ground exploration of the moon or planets such as Mars have proven reliable. They have either been made of semiridged wire mesh or solid rubber. However, they are heavy and can not be collapsed to conserve space. Thus a collapsible tire would be desirable. Tires that can be stored in the collapsed condition and inflated when required are basically old in the art. They are commonly used on automobiles where storage space for a spare tire is sometimes at a minimum. The tires are typically designed to mount on a conventional rim, thus requiring a reinforced bead area so that sealing thereto can be accomplished without the use of an inner tube. U.S. Pat. No. 4,057,091 xe2x80x9cPneumatic Tirexe2x80x9d by J. D. Gardner, et al., U.S. Pat. No. 4,116,255 xe2x80x9cFoldable Pneumatic Tirexe2x80x9d by H. Hayakawa, et al. and U.S. Pat. No. 3,570,572 Collapsible Tirexe2x80x9d by A. Cardenas, et a. are typical examples.
However, while such designs are quite adequate for use on automobiles, they are unsuitable for use on vehicles involved in interplanetary exploration. First of all they are all designed for use with conventional wheel rims and until inflated, one can not be sure that a proper tire to rim seal has been obtained. If there is a leak, there is no way to repair it. Secondly, the use of a conventional tubeless tire to rim seal requires that the tire side walls be stiff, and thus heavier than required for a such missions. Future Mars mission rovers will require very flexible tire walls, have extremely good traction and a very large footprint. The tires will have to be collapsible for storage during transit, but a highly reliable and testable tire to rim seal must be provided.
Thus, it is a primary object of the invention to provide a tire assembly that can be stored in a compact collapsed condition until use is required.
It is another primary object of the invention to provide a tire assembly having an inner tube that can be stored in a compact collapsed condition until use is required.
It is a further object of the invention to provide a tire assembly that can be stored in a compact collapsed and incorporates a protective cover.
It is a still further object of the invention to provide a tire assembly that can be stored in a compact collapsed condition on a vehicle and inflated in place through the rim of the tire assembly.
The invention is a collapsible tire assembly for a vehicle designed to travel over terrain. In particular, the tire assembly is designed for use on vehicles for exploration on the surface of extraterrestrial bodies such as the planet Mars. In detail, the tire assembly includes a rim rotatably mountable to the vehicle. An outer tube expandable from a stored condition to an expanded condition is attached to the rim. The outer tube includes side portions and a center tread portion for making contact with the terrain when in the expanded condition. The side portions thereof are foldable over the center tread portion when the outer tube is in the stored condition.
A mechanism is included for mounting on the side portions of the outer tube to the rim such that the outer tube forms a chamber. This mechanism includes the rim having first and second circumferential flanges on either side thereof. The side portions of the outer tube have first and second circumferential end portions adapted to mate with the first and second circumferential flanges, respectively. First and second ridged retaining rings are adapted to mate with the first and second circumferential flanges, respectively; and fasteners are used to secure the first and second retaining rings to the first and second circumferential flanges with the first and second circumferential end portions of the outer tube secured to the rim therebetween.
An inner tube is mounted within the chamber formed by the rim assembly and outer tire and is expandable from a stored condition within the chamber to an expanded condition forcing the outer tube to its expanded condition. Thus the center tread portion is supported by the inflated inner tube and the tire assembly is suitable for moving the vehicle over the terrain. A port is provided for connecting the inner tube to a source of pressurized gas for inflating the inner tube to the expanded condition. A protective shield is provided for covering the outer tube when in the stored condition. It includes first and second flexible covers having first ends secured to the rim and seconds ends movable to an over lapping position when the outer tube is in said stored condition. A fastener, preferably a hook and loop type, releasably secures the first and second ends of the first and second covers together.
The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description in connection with the accompanying drawings in which the presently preferred embodiment is of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for purposes of illustration and description only and are not intended as a definition of the limits of the invention.